1. Field of the Invention
The present invention relates to reverse osmosis filtration devices, and more particularly, to filtration devices that have flow meters and fluid conductivity meters powered by RFID tags.
2. Description of the Related Art
Reverse osmosis (“RO”) filtration systems typically utilize spiral wound membrane filters. Spiral systems are usually staged with three to eight membrane filter devices connected in series within a pressure tube. The filter devices are connected through adapters on permeate tubes. The permeate from each filter device is combined together as a composite solution in the central tube of subsequent filter devices, connected in series, along the pressure vessel. A permeate in each subsequent filter device, located in the direction of the permeate flow, is the composite permeate of the given filter device combined with permeate from filter devices located upstream of it. In a commercial RO unit, a number of pressure vessels are operating in parallel, having feed, concentrate and permeate ports connected together to corresponding manifolds.
The performance of reverse osmosis systems is monitored by collecting information on flows, pressures and conductivities of feeds, permeates and concentrates of individual filters and the whole system. Knowledge of performance of individual filter devices in respect of product flow and product conductivity is of importance for decisions on selection of filter devices for replacement and to evaluate membrane fouling phenomena in the reverse osmosis filtration system. Some information on permeate conductivity produced by individual filter devices can be obtained by so called “probing” of the pressure vessel. During the probing procedure a small diameter tubing is inserted through the permeate port of the pressure vessel and pushed along permeate tubes of connected elements. Permeate samples are collected at predetermined distances and conductivity is measured. These results represent the conductivity of composite permeate at the given location. The results can be associated with individual elements assuming some value for permeate flow of elements that contributed to the composite permeate flow. The calculated permeate conductivity of individual elements is only approximate and frequently incorrect mainly due to an inability to measure permeate flow at the point of water sample collection inside of the permeate tube.
Presently, more accurate information on performance of individual filter devices is only available off line, and filter devices have to be removed from the pressure vessel and tested individually in the single filter device test unit. Such a procedure is disruptive to plant operation and not practical in large plants. Moreover, results obtained in a single filter device test apparatus can not be accurately projected to the fluctuating operating conditions of larger multi-filter device systems.